Permanent or oxidation haircoloring products constitute the majority of formulas used in modern times. These have the ability to change the color of gray or pigmented hair, as they permanently alter the hair's coloration. Reapplication occurs as the hair's new growth becomes noticeable. Oxidation hair dyes are normally sold in the form of a two-component kit. In one container is an alkaline composition that contains oxidation dyes and an appropriate vehicle. In the other container is a developer composition that utilizes an oxidizing agent, usually hydrogen peroxide. The two compositions are mixed immediately prior to use and applied to the hair. The alkaline pH of the mixture causes the hair shaft to swell, allowing the dye precursors to penetrate into the cortex of the hair. These dye precursors are then oxidized, which combine to form larger molecules. These larger molecules contain a significant level of resonance, hence producing a colored product that is visible from the exterior of the hair. After an appropriate development time, the mixture is rinsed from the hair. The color of the hair is then permanently altered. Depending upon the pH of the mixture and the strength of the developer, these systems can have the capability to lighten the hair's natural pigment, or only deposit color with little lightening action. The so-called “deposit only permanent colors” have played a minor role in retail women's products marketed in the past 30 years, but have a significant share of the professional market. They also make up the majority of men's hair colorants sold today, due to the natural gray blended appearance that the final results impart.
As the minimal lightening products or “deposit only permanent colors” do not require the natural pigment lightening affect produced with the addition of hydrogen peroxide or similar type of oxidizer, attempts have been made to replace or eliminate the developer portion of the oxidation dye products. In regards to replacing hydrogen peroxide, several inventions discuss the use of enzymes or solutions of chlorites. These systems still require two component compositions that are mixed immediately prior to application. Although the alternate developer formulas are milder and produce less damage to the hair, they do not offer any great advantages in relation to improved convenience, messiness, ease of use, or color delivery. The only products that can make that claim are the so-called air oxidation or auto oxidation hair colors that eliminate the entire mixing step. As the name implies, these compositions rely on atmospheric oxygen for color development. No mixing is required. Formulas are applied to the hair for 15-30 minutes and rinsed. Unfortunately, very little color develops within the hair structure using this process. The first practical application of this technology was first discussed in U.S. Pat. Nos. 3,920,384 and 4,054,413. Traditional primary intermediates were combined with couplers that had a high degree of electron donating groups on the aromatic ring. These couplers are more reactive than most dye intermediates, and were able to produce a small amount of color in the hair structure with limited exposure. Since the amount of color developed was minor, the only commercial application for such formulas was in the gradual or progressive hair color field. Consequently, a few products were eventually marketed to men in an attempt to find a safer means of gradually coloring hair. Prior to these products, lead acetate compositions were the only means of accomplishing this. Both types of products require reapplication of the formulas several times a week in order to develop and maintain any degree of gray coverage. To this day these air oxidation gradual haircolors only play a minor role, even in the men's haircoloring arena.
Catalyzed dying systems have been explored in the past for two component oxidation haircolor systems, in an effort to speed up the processing time or produce darker shades on very resistant hair. These rely on some type of pretreatment containing the catalyst (usually a water soluble transition metal salt). The extra pre-treatment step usually made these products impractical for commercial application. Additionally, the build up of copper or iron within the protein matrix left the hair feeling rough and damaged. Attempts to apply the metal catalyst technology to air oxidation color development have been made with limited success. U.S. Pat. No. 4,004,877 uses metal salts complexed with tartaric acid in an air oxidation system. The resulting colors on hair are still very light with a single application. Additionally, the composition requires the use of formamide as solvent. For safety reasons, this material is no longer acceptable for use in cosmetic products. U.S. Pat. No. 6,648,925 takes this technology a step further by capturing the metal catalyst within a clathrate or zeolite compound in an air oxidation composition. These are inclusion complexes where the metal ions are completely enclosed within the crystal structure of another compound. These are difficult formulations to prepare, and are not practical for commercial application. Also, these formulas do not develop enough color on gray hair to produce an entire palette for a typical population. U.S. Pat. No. 7,060,108 teaches the use of iron salts chelated with EDTA compounds in order to enhance dye take with minimal damage. Even under the more extreme dying conditions cited in this patent (30 minutes dwell at 30° C.); formulations tested on hair swatches also do not produce shades comparable to two part “deposit only oxidation haircolor”.
The object of this invention is to provide formulations and manufacturing methods that achieve the level of color deposition, and wear properties equivalent to two part “deposit only oxidation haircolorants”, but from a single component air oxidation product. These formulations use known dye intermediates and other cosmetic ingredients in unique combinations which produce an unexpected degree of gray coverage. Additionally, due to the absence of an oxidizing agent other than atmospheric oxygen, the compositions are milder, less damaging to the hair, and have better color retention than traditional two part systems.